richards
09-10-2007, 01:29 PM
Here's some trivia that I picked up about the Gecko G202 and the G203 stepper drivers:
- The G202 was designed to work best with stepper motors having an inductance rating in the range of 1mH to 40mH.
- The G203v was designed to work best with stepper motors having an inductance rating in the range of 0.5mH to 20mH.
- The PK296A1A-SG3.6 motor (very similar to the motors shipped on many PRT machines) has a full-coil inductance rating (series connection) of 31mH and a half-coil inductance rating (unipolar connection) of 8mH.
- If the PK296A1A-SG3.6 motor is used with the Gecko G203v drive, the motor should be connected to the drive using the half-coil wiring connections.
- Using the formula SQRT(inductance) X 1000, you can find the highest voltage at which to run the motor. For instance, the square root of 8mH is 0.0894 and 0.0894 X 1000 is 89.4 volts. Since the Gecko stepper drivers are limited to a maximum of 80V, you could use a power supply with that motor up to 80V, but a power supply of 65V would still give you excellent performance with much less heat.
Many thanks to Gerald Dorrington for passing along that information. That data corresponds exactly with the tests that I've run during the last two years with the G202, the G203 and lots of different stepper motors. Gerald also forwarded on part of an email from Mariss at Gecko who had wired up a PK296A1A-SG3.6 motor using half-coil connections and a current limiting resistor to let the motor pull 2A from the G203v. Mariss reported, "The 8mH version of that motor performs flawlessly with a stock G203V and outputs 82Watts mechanical at 65VDC compared to 39V for the 1A, 31mH motor."
Although I use the PK296B2A-SG3.6 motors at 25VDC to 35VDC, it looks like I could have gotten excellence performance from the PK296A1A-SG3.6 motor at 65VDC (as long as I wired it half-coil).
- The G202 was designed to work best with stepper motors having an inductance rating in the range of 1mH to 40mH.
- The G203v was designed to work best with stepper motors having an inductance rating in the range of 0.5mH to 20mH.
- The PK296A1A-SG3.6 motor (very similar to the motors shipped on many PRT machines) has a full-coil inductance rating (series connection) of 31mH and a half-coil inductance rating (unipolar connection) of 8mH.
- If the PK296A1A-SG3.6 motor is used with the Gecko G203v drive, the motor should be connected to the drive using the half-coil wiring connections.
- Using the formula SQRT(inductance) X 1000, you can find the highest voltage at which to run the motor. For instance, the square root of 8mH is 0.0894 and 0.0894 X 1000 is 89.4 volts. Since the Gecko stepper drivers are limited to a maximum of 80V, you could use a power supply with that motor up to 80V, but a power supply of 65V would still give you excellent performance with much less heat.
Many thanks to Gerald Dorrington for passing along that information. That data corresponds exactly with the tests that I've run during the last two years with the G202, the G203 and lots of different stepper motors. Gerald also forwarded on part of an email from Mariss at Gecko who had wired up a PK296A1A-SG3.6 motor using half-coil connections and a current limiting resistor to let the motor pull 2A from the G203v. Mariss reported, "The 8mH version of that motor performs flawlessly with a stock G203V and outputs 82Watts mechanical at 65VDC compared to 39V for the 1A, 31mH motor."
Although I use the PK296B2A-SG3.6 motors at 25VDC to 35VDC, it looks like I could have gotten excellence performance from the PK296A1A-SG3.6 motor at 65VDC (as long as I wired it half-coil).